This invention relates to an improved thermoformed cassette album. It is particularly useful for shipping and storing audio books and similar cassettes. The invention provides an album in which a single plastic sheet provides stiffness for both the front and back cover. Both the inner and outer surfaces of the front cover are capable of receiving print such as the title, directions and the like. Crack resistant hinges are provided through the provision of a three-layer laminate wherein inner and outer layers are rendered relatively supple by means of a plasticizer.
In the prior art, the problem of cracking at the hinge along each edge of the spine has been recognized. For example, as described in U.S. Pat. No. 4,407,410, the seals commonly used along each edge of the spine are eliminated. Instead, the spine bows outwardly and flexes across its entire width. This, however, gives the back of the spine a characteristic curved shape which is not always suitable. The covers are reinforced by cardboard insert sheets which add to the cost of the package and require additional manufacturing steps. U.S. Pat. No. 3,315,718 employs a tray and a flat cover formed from separate sheets. The device is made stiff using insert sheets. U.S. Pat. No. 3,441,371 describes a display package formed from two sheets, one of which is formed into a tray shape. Thermoformable sheet material of the type used in forming trays has poor print receiving characteristics and is not considered in the trade to be print receptive. As a result, instructions cannot be printed on the inside of the front cover. Moreover, the hinges on either side of the spine have a tendency to crack after the device has been used for a time rendering it unsightly or nonfunctional.
Another shortcoming of prior albums is that hinges are of necessity spaced from the tray because the tray must have flanges on its periphery. The resulting space between the hinges and the tray allows the cover to slide from side to side on the tray which is, of course, undesirable.
One object of the invention is to provide an improved thermoformed composite cassette album having crack resistant seams on either side of its spine and a front cover that is receptive to printing ink on its inside surface.
Another object of the invention is to provide an improved thermoformed composite album in which a single stiff backing sheet extends throughout both the front and back covers and through the spine region serving to stiffen both the front and rear covers and includes improved hinges on either side of the spine with a provision for preventing the thermoformed hinges from cracking after a short period of use.
A still further object of the invention is to provide a strong, rugged, reliable album cover having sufficient stiffness and being simplified in construction through the elimination of parts which allows it to be manufactured more efficiently and economically.